The present invention relates to an improved coating tray for providing a uniform coat of fluid material on sheet stock such as a stencil screen.
Many existing screen coating apparatus employ reservoirs holding a screen coating fluid such as a photoresist and provide an adjustable flow rate through apertures therein to supply the desired thickness of coating as the coating reservoir is moved across the screen at a uniform speed. Copending patent application entitled PRINTING SCREEN COATING APPARATUS AND METHOD, Ser. No. 258,856, filed June 1, 1972, now U.S. Pat. No. 3,834,348, and assigned to the present assignee describes coating apparatus in which a coating fluid is controllably discharged by a tray reservoir and evenly spread by means of a rake-like follower blade having a plurality of teeth contacting the screen and distributing the fluid as it is applied to the screen.
Although such coating apparatus performs adequately for most applications, the flow rate control mechanism is relatively complex and requires periodic cleaning and maintenance to assure the flow rate will be constant for the desired setting to assure a uniform coating of desired thickness.